[FIR] Add // FIR_DUMP to some implicit invoke tests

Although these dumps don't really show if
something is a `FirFunctionCall` or a
`FirImplicitInvokeCall`, they do show what
goes into the receiver, and what are value
arguments.

compiler/testData/diagnostics/tests/expressionsInQaSelectorsWithElvis.kt

@@ -1,5 +1,6 @@
 // FIR_IDENTICAL
 // ISSUE: KT-64891
+// FIR_DUMP
 
 fun test(a: (Int.() -> Int)?, b: Int.() -> Int) {
     2.(a ?: b)()